I'd love to see the ability to theme the title bar in the same way we can theme the status bar (or any other element for that matter). Its one of the last remaining elements necessary to truly fulfill the ProKit theme https://forum.sublimetext.com/t/theme-aqua/5734/1.
That would actually be useful indeed.
In particular, I'd like to be able to put the project title before the file in the window title! Would make it much easier to identify one of my several sublime windows!
This would easily be achievable if Sublime was to act like Chrome and other applications (Chrome wasn't the first to put tabs in the titlebar).
It would be really nice if Sublime had tabs within the title bar just like Chrome